Line graphs are a way of representing two variables. One variable is plotted along vertical axis and the other along the horizontal axis. Line graphs are good at showing specific values of data. For a value of one variable, the value of the other can easily be determined. Line graphs can show trends in data clearly, meaning that they visibly show how one variable is affected by the other as it increases or decreases. Just a look will show whether a particular variable is increasing or decreasing and how it behaves over a period of time. Sudden dips or increases can also be seen without much effort. A line chart thus displays information as a series of data points connected by straight-line segments. Line charts are very helpful to visualize a trend in data over intervals of time.
Some characteristics of line graphs are:
1. Data is given precisely in tables, but a line graph, or in all graphical representations, give only an approximate idea. The values will have to be read on the graph or calculated.
2. The picture it gives is more vivid in showing the trends and comparisons than mere numbers.
3. It indicates the variation of a parameter with respect to another variable. These parameters are calibrated on the X and Y axis.
4. Slope is an important observation in line graphs. It helps in comparing the magnitude of change between any two consecutive points on graph. The steeper the slope, greater is the change in magnitude between two consecutive points.
In the experimental sciences, data collected from experiments are often visualized by a graph that includes an overlaid mathematical function depicting the best-fit trend of the scattered data. This layer is referred to as a best-fit layer and the graph containing this layer is often referred to as a line graph.